1. Field of Invention
The present invention pertains to the field of solid-state memories. More particularly, this invention relates to a solid-state memory with magnetic storage cells.
2. Art Background
Solid-state memories have a wide variety of applications particularly in computer systems. Prior solid-state memories are usually constructed of semi-conductor materials. For example, prior semiconductor memories include dynamic random access memories (DRAMs) as well as persistent or non-volatile memories such as flash memories to name a few.
A prior solid-state memory is typically arranged as one or more arrays of memory cells or storage cells. The structure of each storage cell usually provides a mechanism for storing a bit of information. For example, the storage cells in a typical DRAM include structures that form a capacitor for storing information as an electrical charge. In addition, the storage cells in a typical flash memory include structures that form a floating-gate for persistent storage of an electrical charge.
Typically, such specialized structures in prior solid-state memories require critical alignment in order to achieve high storage cell densities. For example, high density DRAM cells usually require critical alignments in the trenched or stacked capacitor structures contained therein. In addition, flash cells typically require critical alignment among the floating-gate structures contained therein.
Such storage cell structures are usually formed using multiple pattern masks according to the particular process technology used for fabrication of the solid-state memory. Typically, the critical alignments of such structures requires a relatively precise alignment among the pattern masks. Unfortunately, process technologies that achieve precise alignment of pattern masks are usually expensive and therefore greatly increase the cost of prior high density solid-state memories.
In addition, prior solid-state memories usually are formed on single crystalline semiconductor materials. Unfortunately, the requirement of a crystalline semiconductor substrate limits the flexibility in which any storage cells may be arranged. For example, a typical crystalline semiconductor substrate used for fabricating prior solid-state storage cells usually precludes the stacking of arrays of DRAM or flash storage cells into multiple layers. Such limitations limit the storage densities that may be achieved with prior solid-state memories.
A solid-state memory is disclosed which includes an array of magnetic storage cells and a set of conductors coupled to the magnetic storage cells. The solid-state memory is manufactured so that the process steps that pattern the conductors also pattern the magnetic layers in the magnetic storage cells, thereby avoiding the need to employ precise alignment between pattern masks. In addition, the magnetic storage cells are not formed on a single crystalline semiconductor substrate. As a consequence, the arrangement of magnetic storage cells is not limited by the inherent limitations of such substrates.
Other features and advantages of the present invention will be apparent from the detailed description that follows.